It's claimed commuters using the Thameslink rail line which runs from Bedford to London may have to wait longer for improved services.
While changes have been made, including longer trains and the current redevelopment of Blackfriars and London Bridge stations, the National Audit Office is concerned progress is too slow.
More top news
A three-storey house has collapsed and businesses have been destroyed following a major fire on a historic high street near Milton Keynes.
Children in a Suffolk school have been mourning the loss of a teenager who was killed by an airgun over the weekend.
Campaigners want to turn Southwold's former cottage hospital into a community hub rather than allow developers to create more holiday homes